This invention relates to photographic cameras and, more particularly, to a mechanism for compensating and transmitting diaphragm values in an F-value variable zoom lens.
With the zoom lenses of various types in which the fully opened diaphragm value (generally referred to as F-value) of the lens is variable, not only the maximum aperture value, but also the aperture ratio, change as operation of zooming progresses. Application Ser. No. 229,879, filed Jan. 30, 1981, application Ser. No. 235,839, filed Feb. 19, 1981, and application Ser. No. 235,840, filed Feb. 19, 1981, are directed to automatic exposure control in a camera having interchangeable lenses, each having different maximum aperture values. The disclosures of these applications are incorporated fully herein by reference. In particular, application Ser. No. 235,839 discloses a system for accommodation of changes in lens characteristics by which a desired compensation is achieved by introducing a preliminary stroke, i.e., displacement, in the release operation that takes no part in the actual stop down process.